Titanium alloys



'tics at elevated temperatures.

United States Patent TITANIUM ALLOYS Earl F. Swazy, Richard H. Freyer, and Lee S. Busch, Indianapolis, Ind., assignors, by mesne assignments, to Mallory-Sharon Titanium Corporation, Indianapolis, Ind., a corporation of Indiana No Drawing. Original application January 13, 1950, Serial No. 138,516, now Patent No. 2,661,286, dated December 1, 1953. Divided and this application September 4, 1953, Serial No. 382,183

3 Claims. (Cl. 75-1755) This invention relates generally to alloys of titanium and has particular reference to alloys consisting of titanium, carbon and silicon, alone, or in combination with another element, to form a quaternary alloy with titanium predominating. This application is a divisional application of Serial No. 138,516, now United States Patent No. 2,661,286.

An object of the present invention, therefore, is to provide Wrought, ductile alloys of titanium.

Another object of the present invention is to provide a Wrought, ductile alloy of titanium, carbon and silicon.

Still another object of the invention is to provide quaternary alloys of titanium.

Yet another object of the invention is to provide alloys of titanium consisting of titanium, carbon and silicon having greater resistance to oxidation at elevated temperatures than pure titanium and exhibiting good hardness characteristics thereof.

Another object of the invention is to provide an alloy of titanium consisting of titanium, carbon and silicon and any one of the following elements: aluminum, copper, vanadium, chromium, boron, tungsten and iron.

Still another object of the invention contemplates a method of preparing ternary alloys of titanium consisting of titanium, silicon and carbon with titanium predominating.

Yet another object of the invention contemplates a method of preparing quaternary alloys of titanium consisting of the ternary alloys of carbon, silicon and titanium, to which is added an element from the group; aluminum, copper, chromium, vanadium, boron, tungsten or iron.

Another object of the invention is to provide a method of fabricating ductile, hot forged alloys of carbon, titanium, and silicon, to which may be added any one of the elements: aluminum, copper, chromium, vanadium, boron, tungsten or iron, said alloys having a tensile strength exceeding 100,000 p. s. i. and more generally that above 120,00 p. s. i.

The invention, in another of its aspects, relates to the novelfeatures and principles teaching the objects of the invention and to the novel principles employed herein whether or not these features and principles may be used in said object or in said field.

It is found that alloys of titaium, silicon and carbon with titanium predominating as a ternary alloy, or as an alloy to which may be added another element such as aluminum, chromium, copper, vanadium, boron, tungsten or iron provide a resistance to oxidation at elevated temperatures greater than that of pure titanium. Such alloys provide ductile, strong alloys of titanium and exhibit good corrosion resistance and high hardness characteris- These alloys are usually manufactured by melting and casting in a graphite retort under an inert or neutral atmosphere; for example, argon,

or in a vacuum. Further, the alloys may also be prepared by powder metallurgy methods. Thus, as an example, alloys containing .1% to 10% silicon, .2% to 2% 2,786,756 Patented Mar. 26, 1957 carbon with the balance titanium, as compared to pure titanium, are characterized by having a higher tensile strength, equivalent ductility, slightly higher electrical resistivity, much better resistance to oxidation at elevated temperatures and high hardness at temperatures up to 600 C. Further they may be hot or cold worked by the usual methods known to the art.

As a further example, hereof, an alloy made by mixing silicon powder and titanium powder or sponge, and melting and casting in graphite in argon gas, contained 0.992% silicon, .47% carbon, with the balance titanium. This alloy had the following properties as hot forged to reduction in area (equivalent properties of titanium containing .477% carbon only are included for comparison).

.477% Carbon- .992% Silicon-.47% Balance Titanium Oarbon13alance Titanium Ultimate Tensile Strength. 105,000 p. s. i Elongation in 2" 12 57 Moreover, alloys, such as above, are characterized by a unique response to heat treatment. Upon quenching from 1000 0., these alloys do not harden appreciably. (Most alloys of titanium which contain metals forming stable carbides do harden on quenching.) However, as the tensile strength is lowered to 113,500 p. s. i., the elongation increases to 16.5%. In the as forged condition, the hardness at 600 C. increases from 0 Rockwell A to 32 Rockwell A when quenched. These changes are apparently caused by the presence of large amount of B titanium (body centered cubic) which is not transformed to a on fast cooling from 1000 C.

Again, in resistance to sealing tests at 900 C., an alloy containing 992% silicon was three times as effective as that for titanium containing .47% carbon. The results revealed a .53 6% increase in weight for the silicon alloy and 1.89% for the titanium alloy containing carbon only.

The ternary alloy consisting of titanium, silicon, and carbon may be combined with another element, for example, aluminum, to give an alloy of titanium, aluminum, silicon and carbon. This alloy is ductile and stronger than pure titanium and like the ternary alloy has good resistance to oxidation at elevated temperatures. Similarly, it exhibits better corrosion resistance and hardness at elevated temperatures than does pure titanium. As with the ternary alloy above described, an alloy of aluminum, silicon, carbon and titanium with titanium predominating, exhibits adequate ductility and susceptibility to hardening, as by quenching in water or other media, under subsequent cooling from elevated temperatures e. g. 1000" C. The quaternary alloys of aluminum, silicon, carbon and titanium, may be manufactured in a manner similar to those of the ternary alloys; that is, they may be fabricated by melting and casting under an inert or neutral atmosphere (for example, argon) or in a vacuum. The alloys may also be prepared by powder metallurgy methods. A preferred method consists of mixing alumimum and silicon, in mass or powder form, with titanium in sponge or powder form and then melting and casting in graphite. These alloys are preferably forged in air at temperatures between 800 C. to 900 C. but may be hot or cold worked by the usual methods known to the art.

These alloys may contain small but significant amounts of aluminum, silicon and carbon; that is, up to 5% aluminum, up to 5% silicon; and up to 2% carbon. The lower limit established is 0.1% aluminum, 0.1% silicon, 0.1% carbon. A practical range of composition is from 0.5%

to 3% aluminum; from 0.5 to 3% silicon; from 0.3% to 0.7% carbon and the balance titanium.

Such an alloy (titanium; silicon, carbon, aluminum) prepared by this inventionhas the following minimum properties:

Ultimate, tensile strength 120,000 p. s. i. Elongation in 2" 5%.

Modulus of elasticity 15. '10 p. s. i. Electrical resistivity 75 1.0- ohm-cm.

As stated, the ternary alloys formed of titanium, silicon and carbon may be combined with one of the elements: aluminum, copper, chromium, vanadium, boron or tungsten to form quaternary alloys. Thus, such an alloy consisting of titanium, copper, silicon and carbon exhibits the characteristics recited previously for the above alloys; i. e., ductility, high resistance to oxidation, better corros'ion' resistance, higher hardness, etc.

These alloys (titanium, copper, silicon and carbon) may be manufactured by melting and casting under an inert oi neutral atmosphere (for example, argon) or in a vacuum. The alloys may also be prepared by powder metallurgy methods. A preferred method would thusconsist in mixing copper and silicon, in massive or powder form, with titanium in sponge or powder form and melting and casting in graphite. The source of the carbon is the crucible and the amount is easily controlled by varying the time that the charge is. molten. The alloys are preferably forged in air at temperatures between 800 C. and 900 C. but may be hot or cold worked by the usual methods known to the art.

The quaternary alloys of titanium, copper, silicon and carbon, herein described, may be made containing small but significant amounts of copper, silicon and carbon: for example, up to 10% copper; up to 10% silicon; and up to 2% carbon with the balance being titanium. The lower limit for these alloys is. 0.1% copper; 0.1% silicon; 0.1% carbon and the balanEe titanium. A practical range of composition may be 1% to 5% copper; 0.5% to 3% silicon; 0.3% to 0.7% carbon and the balance titanium.

Such alloys prepared by this invention have thefollowing minimum properties: I

As quenched from 600 0. t 1,100 C.

As Hot Forged Still other alloys may be fabricated of titanium, chro mium, silicon, and carbon. These are also formed as by melting and casting under an inert or neutral atmosphefe (for example, argon) or in a vacuum. Again, such alloys may also be prepared as by powder metallurgy methods. For example, in the fabrication of this alloy, a. preferred method consists of mixing chromium and silicon, in massive or powder form, with titanium in sponge or powder form and melting and casting in graphite. The source of the carbon, once more, is the crucible and'the amount thereof is easily controlled as by varying the. time that the charge is molten. The alloys of titanium, carbon, chromium and silicon are preferably forged in air at temperatures between 800 C. to 900 C. but may be hot or cold worked by methods known to the art.

Such alloys contain small but significant amounts of chromium, silicon and carbon; that is, up to 10% chromium; up to silicon and up to 2% carbon with the balance being titanium. The lower limit is 0.1% chromium, 0.1% silicon, 0.1% carbon and the balance titanium. A practical range of this composition is from 1% to 5% chromium; from .5 to 2% silicon; from 0.3% to 0.7% carbon and the balance titanium.

4 Alloys of titanium, carbon, chromium and silicon by this invention have the following minimum properties:

Ultimate tensile strength 125,000 p. s. i. Elongation in 2" 5%.

Modulus of elasticity l8 l0 p. s. i. Electrical resistivity 75- 10- ohm-cm.

As an example of the formation or fabrication of an alloy utilizing the ternary base alloy titanium, silicon and carbon and an added element, such. as vanadium, is an alloy consisting of small but significant amounts of vana- *dium, siiiconand carbon; that is, up to 10% vanadium; up to 5% silicon; and upto 2% carbon, with the balance being titanium. The lower limit for the alloy is 0.1% vanadium, 0.1 silicon and 0.1% carbon and the balance titanium. A practical range of the composition is 1% to 5% vanadium; 0.5% to 3% silicon; 0.3% to 0.7% carbon with the balance titanium.

As with the other alloys these; alloys exhibit better resistance to oxidation at elevated temperatures, better corrosion resistance, higher ultimate tensile strength and higher hardness at elevated temperatures than does pure titanium. In addition these alloys are characterized as being adequately ductile and susceptible to hardening by quenching in water or other media.

The alloys of' this invention may be manufactured by melting and casting under an inert or neutral atmosphere (for example, argon) or in a. vacuum. The alloys may also be prepared by powder metallurgy methods. A preferred method consists of mixing vanadium and silicon in massive or powder form, with titanium in sponge or powder form, and melting and casting in graphite. The source of the carbon is the crucible and so the amount is easily controlled by varying the time. the charge is molten. The alloys are preferably forged in air at temperatures between 800 C. to 900 C. but may be hot or cold'worked by the methods known in the art. a

These alloys prepared have the following minimum properties in the hot forgedcondition:

Ultimate tensile strength 125,000p. s. i.

. Elongation in 2" 8%.

Modulus of elasticity 16x10 p..s. i. Electrical resistivity 75 x10 ohm-cm.

Another quaternary alloy which may be fabricated from the ternary alloys of titanium, carbon and silicon is the alloy of boron, silicon, titanium and carbon. v Alloys thus formed are ductile and are stronger than pure titanium. They have considerably better resistance to oxidation at elevated temperatures and like the other quaternary alloys described exhibit bettep corrosion resistance and higher hardness at elevated temperatures than those of pure titanium. For example, the resistance to oxidation at 900 C. is found to be. much better than pure titanium or titanium with carbon present only. The alloys of titanium, silicon, boron and carbon may be fabricated as described by the methods above; such as melting and casting in an inert and neutral atmosphere (for example, argon) or in a vacuum. These alloys, too, may be prepared by powder metallury methods. Thus, a preferred method consists of mixing silicon and boron .in massive or powder form with titanium in sponge or powder form and melting and casting in agraphite. crucible. Since the source of the carbon is the crucible, the amount is easily controlled by varying the time the chargeis molten. The alloys may be forged in air at temperatures. between 800 C. to 900 C. and may be hot or cold worked by the methods known to the art.

The alloys of titanium, carbon, silicon and boron as here described, may be made. consisting of small but significant amounts of silicon, boron and carbon: that is, up to 5% silicon; up to 5% boron; and up to 2% carbon; the balance being titanium. A practical range of composition is .5% to 3% silicon; 0.5% to 2.0% boron; 0.3%. t0-0.7% carbon; the balance being titanium.

These alloys have the following minimum properties in the hot forged condition:

Alloys of titanium, tungsten, silicon and carbon have also been fabricated exhibiting substantially the same qualities as the other alloys depending upon the base ternary alloy of titanium, carbon and silicon. In this case the element tungsten is added to the base alloy above. These alloys, utilizing tungsten, may be similarly manufactured as previously described and also may be prepared according to powder metallurgy methods.

For example, a preferred method consists of mixing tungsten and silicon in massive or powder form with titanium in sponge or powder form and melting and casting in graphite. Again, the source of the carbon is the crucible or retort so the amount is easily controlled by varying the time the charge is molten. The alloys are preferably forged in air at temperatures between 800 C. and 900 C. but may be hot or cold worked by the usual methods known to the art.

The alloys of titanium, carbon, silicon and tungsten, here described, may be made containing small but significant amounts of tungsten, silicon and carbon: that is, up to tungsten; up to 5% silicon; and up to 2% carbon; the balance being titanium. The lower limit therefor is 0.1% tungsten; 0.1% silicon; 0.1% carbon; and the balance titanium. A practical range of composition is 0.5% to 5% tungsten; 0.5% to 3% silicon; 0.3% to 0.7% carbon; and the balance titanium.

Alloys thus prepared have the following minimum properties:

As Hot Forged As quenched from 600 C. to 1,000 C.

Ultimate Tensile Strength 120,000 p. s. 1..-... 135,000 p. s. i. Elongation in 2 7 o 3 Modulus of Elasticity. 10 p. s. i... 18X10 p. s. i.

Electrical Resistivity 70X10- ohm-cm." 70X10- ohm-cm.

Again a base alloy of titanium, silicon and carbon may be combined with the element, iron, to form a new quaternary alloy titanium, iron, silicon and carbon. These alloys of titanium, iron, silicon, and carbon are ductile and provide alloys of titanium which are stronger than titanium and have better resistance to oxidation at elevated temperatures. These alloys further exhibit better corrosion resistance and high hardness at elevated temperatures than those of pure titanium.

These alloys are characterized by adequate ductility even through the ductility is less than that of pure titanium. Moreover, the alloys of this invention are susceptible to hardening by quenching in water or other media. Alloys in the quenched state have ultimate tensile strengths of approximately 175,000 p. s. i. and elongation in 2" of about 4%.

The alloys of this invention containing iron may be manufactured by melting and casting under an inert or neutral atmosphere (for example, argon) or in a vacuum. The alloys may also be prepared by powder metallurgy methods. A preferred method consists of mixing iron and silicon in massive or powder form with titanium in sponge or powder form and melting and casting in graphite. Since the source of the carbon is the crucible the amount is easily controlled by varying the time the charge is molten. The alloys are preferably forged in air at temperatures between 800 C. to 900 C. but may be hot or cold worked by the usual methods known to the art.

The alloys herein described may be made containing small but significant amounts of iron, silicon and carbon;

that is, up to 10% iron; up to 5% silicon; up to 2% carbon; and the balance titanium. The lower limit is 0.1% iron; 0.1 silicon; 0.1% carbon; and the balance titanium. A practical range of composition is 1% to 5% iron, 1% to 3% silicon, 0.3% to 0.7% carbon and the balance titanium.

Alloys of iron prepared according to this invention exhibit substantially the following minimum properties:

The following chart is useful in depicting the constituents of the above described alloys.

Alloy table Alloy Ti, per- Si, per- 0, per- Andcent cent cent (1) 1, Si, 99. 7-88 1-10 2-2 (2) T1, Si, C+ 99 7-88 .1-5 .1-2 1-5% Al (3) Ti, Si, C+Ou 99. 7-78 1-10 .1-2 l10% Cu (4) Ti, Si, C+Or, 99. 7-83 1-5 .l-2 1-10% Cr (5) Ti, Si, 0+V. 99. 7-83 1-5 1-2 1-10% V (6) Ti, Si, C-l-B. 99. 7-88 l-5 .1-2 1-5% B (7) Ti, Si, 0+W. 99. 7-83 1-5 1-2 1l0% W (8) Ti, Si, C-l-Fe 99. 7-83 1-5 1-2 1-10% Fe Thus, it is seen that by the present invention primary, ductile, ternary alloys of titanium, silicon and carbon may be formed presenting characteristics substantially superior to pure titanium in matters of resistance to oxidation, resistance to corrosion and high hardness. In addition, these ternary alloys may be combined with any one of the elements; aluminum, copper, chromium, vanadium, boron, tungsten or iron. Thus, a basic ternary alloy consists of from .1% to 10% silicon; from .2% to 2% carbon with the remainder being substantially all titanium. Several of the quaternary alloys may consist of up to 10% silicon; up to 2% carbon; and up to 10% of either chromium, vanadium, tungsten or iron; the remainder being substantially all titanium. Further, quaternary alloys of titanium, silicon, carbon and aluminum; and titanium, silicon, carbon and boron may be fabricated wherein the silicon is present in amounts up to 5%; carbon in amounts up to 2%; and either aluminum or boron in amounts up to 5% of the alloy, the remainder of the total amount being supplied by the titanium. Again, an alloy, according to this invention may be fabricated of titanium, silicon, carbon and copper. In such an alloy, silicon and copper each may be present in amounts up to 10%; carbon up to 2%; with the remainder thereof being titanium.

While the present invention as to its objects is merely illustrative and not exhaustive in scope and since many widely different embodiments of the invention may be made without departing from the scope thereof, it is intended that all mater contained in the above description be interpreted as illustrative and not in a limiting sense.

We claim:

1. Alloys containing from 0.1% to 5.0% aluminum, from 0.1% to 5.0% silicon, from 0.1% to 2.0% carbon, and the remainder being substantially all titanium.

2. Alloys containing from 0.5% to 3% aluminum, from 0.5% to 3% silicon, from 0.3% to 0.7% carbon, and the balance being substantially all titanium, said alloys ng. q nch har n nd hich can e s bseq e tly anneal d- 3. The alloys of titanium as in claim 2 having the 01- lq m nimum pr p rt es:

Ultimate tensile s.tr .ugth i 120,000 p, s. i. Elongation in 2" 5%.

Modulus of e1asticity 15 x10 p. s. i. Electrical resistivity-, 75 10 ohm-cm.

References Cited in the file. of this patent 

1. ALLOYS CONTAINING FROM 0.1% TO 5.0% ALUMINUM, FROM 0.1% TO 5.0% SILICON, FROM 0.1% TO 2.0% CARBON, AND THE REMAINDER BEING SUBSTANTIALLY ALL TITANIUM. 